Optical film and display module

Abstract

This application provides an optical film, including: a first dielectric layer; a second dielectric layer, which are alternately stacked with the first dielectric layer to form a stacked structure, wherein the refractive index of the second dielectric layer is less than the refractive index of the first dielectric layer adjacent to it.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to an optical film and a display module. Background Technology

[0002] A direct-lit display device is a type of display device that places a light-emitting diode (LED) or similar light source behind the panel, allowing the panel to directly illuminate the image. Compared to edge-lit displays, direct-lit displays offer advantages such as a wider color gamut, higher contrast, and greater brightness, but they are relatively thicker, making it less conducive to achieving a thinner and lighter design. Summary of the Invention

[0003] This application provides an optical film and a display module that can reduce the thickness of direct-lit display devices and achieve a thinner and lighter structure.

[0004] On one hand, embodiments of this application provide an optical film, including: a first dielectric layer; a second dielectric layer, which are alternately stacked with the first dielectric layer to form a stacked structure, wherein the refractive index of the second dielectric layer is less than the refractive index of the first dielectric layer adjacent to it.

[0005] In some embodiments, the optical thickness of the first dielectric layer is l1, then Where λ1 is the wavelength of visible light in the first dielectric layer, and k is a natural number.

[0006] In some embodiments, the optical film includes multiple layers of the first dielectric layer, wherein the refractive indices of the first dielectric layers located in different layers are the same or different; and / or, the thicknesses of the first dielectric layers located in different layers are the same or different.

[0007] In some embodiments, the optical film comprises multiple layers of the second dielectric layer, wherein the refractive indices of the second dielectric layers located in different layers are the same or different; and / or, the thicknesses of the second dielectric layers located in different layers are the same or different.

[0008] In some embodiments, any second dielectric layer is disposed between two first dielectric layers.

[0009] In some embodiments, the optical film further includes a light-concentrating layer disposed on the light-incident side of the stacked structure.

[0010] In some embodiments, the light-concentrating layer has a prism structure, a pyramid structure, or a convex lens structure; and / or, the light-concentrating layer is multi-layered, with the multiple light-concentrating layers stacked sequentially.

[0011] In some embodiments, the optical film further includes a light diffusion layer disposed on the light-emitting side of the stacked structure.

[0012] In some embodiments, the light diffusion layer has a prism structure, a pyramid structure, or a convex lens structure; and / or, the light diffusion layer is multilayered, with the multiple light diffusion layers stacked sequentially.

[0013] On the other hand, this application provides a display module including the optical film described in any of the above embodiments, having an incident light side and an emitted light side disposed opposite to each other; and a light-emitting unit disposed on the incident light side of the optical film.

[0014] In some embodiments, the display module further includes a reflective sheet disposed on the side of the light-emitting unit away from the optical film.

[0015] This embodiment of the application, by alternately stacking a first dielectric layer and a second dielectric layer, and making the refractive index of the second dielectric layer less than that of the adjacent first dielectric layer, allows for selective transmission of light emitted from the light source in the longitudinal direction, resulting in stronger reflection of small-angle light and stronger transmission of large-angle light, and diffusion in the lateral direction. This achieves uniform light intensity and thorough mixing of the three primary colors in different areas, resulting in similar light intensity and rich, realistic colors in different areas of the panel during light display, thus achieving a uniform display effect. In this way, there is no need to set a light mixing gap between the optical film and the light source, nor is it necessary to increase the density of the light source arrangement or the thickness or number of light diffusion plates. The application of light diffusion plates can be eliminated, reducing the thickness of the corresponding structure. Since the optical film itself is thin, the thickness of the direct-lit display device can be reduced, achieving a lightweight structure. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a first cross-sectional view of the optical film provided in some embodiments of this application;

[0018] Figure 2 This is a second cross-sectional view of the optical film provided in some embodiments of this application;

[0019] Figure 3 This is a third cross-sectional view of the optical film provided in some embodiments of this application;

[0020] Figure 4 This is a fourth cross-sectional view of the optical film provided in some embodiments of this application;

[0021] Figure 5 This is a fifth cross-sectional view of the optical film provided in some embodiments of this application;

[0022] Figure 6 These are cross-sectional structural diagrams of display modules provided in some embodiments of this application;

[0023] Figure 7 These are simulation results of the control group of the display module provided in some embodiments of this application;

[0024] Figure 8 These are simulation effect diagrams of display modules provided in some embodiments of this application.

[0025] Description of main component symbols:

[0026] 100-Display module, 1-Optical film, 10-First dielectric layer, 20-Second dielectric layer, 30-Concentrating layer, 40-Light diffusion layer, 2-Light emitting unit, 3-Reflective sheet. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0030] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0031] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0032] In related technologies, direct-lit display devices require a light diffuser between the light source and the panel. The light diffuser scatters the light emitted by the light source, achieving a soft and uniform display effect on the panel. A certain light mixing gap is provided between the light source and the light diffuser. The combination of the light diffuser and the light mixing gap results in a relatively large thickness for the direct-lit display device.

[0033] In related technologies, some direct-lit display devices significantly compress the distance between the light source and the diffuser plate, bringing the distance between them close to zero. This, in turn, compresses the distance between the light source and the panel, achieving a reduction in overall device thickness. However, this also compresses the light mixing gap between the light source and the diffuser plate, making it difficult to ensure sufficient mixing and uniform scattering of the three primary colors. To address this, these direct-lit display devices reduce the spacing between light sources and increase their density, while simultaneously increasing the thickness or number of diffuser plates to offset the negative impact of reduced light mixing gap on light mixing sufficiency and scattering uniformity. However, a denser arrangement of light sources increases the difficulty of circuit layout and overall temperature control, leading to higher costs. Conversely, increasing the thickness or number of diffuser plates negates the aforementioned thinning effect, resulting in a failure to significantly reduce the overall device thickness.

[0034] like Figures 1-4As shown, this application embodiment provides an optical film 1, which includes a first dielectric layer 10 and a second dielectric layer 20, which can reduce the thickness of a direct-lit display device and achieve a thinner structure. Here, the first dielectric layer 10 and the second dielectric layer 20 are alternately stacked to form a stacked structure, and the refractive index of the second dielectric layer 20 is less than the refractive index of the adjacent first dielectric layer 10. Figure 1 As shown, in some examples, the stacked structure may consist of only one first dielectric layer 10 and one second dielectric layer 20, with the first dielectric layer 10 and the second dielectric layer 20 stacked together, and the refractive index of the second dielectric layer 20 being less than that of the first dielectric layer 10; for example... Figure 2 As shown, in other examples, the stacked structure may include a first dielectric layer 10 and two second dielectric layers 20, with the two second dielectric layers 20 respectively disposed on both sides of the first dielectric layer 10, and the refractive index of any second dielectric layer 20 being less than the refractive index of the first dielectric layer 10; for example... Figure 3 As shown, in some other examples, the stacked structure may include two first dielectric layers 10 and one second dielectric layer 20, with the second dielectric layer 20 sandwiched between the two first dielectric layers 10. The refractive index of the second dielectric layer 20 is less than the refractive index of the two first dielectric layers 10. Figure 4 As shown, in some other examples, the stacked structure may include at least two first dielectric layers 10 and at least two second dielectric layers 20, which are alternately arranged in sequence, such that a second dielectric layer 20 is provided between any two adjacent first dielectric layers 10, and the refractive index of the second dielectric layer 20 is less than the refractive index of the two first dielectric layers 10, and a first dielectric layer 10 is also provided between any two adjacent second dielectric layers 20, and the refractive index of the first dielectric layer 10 is greater than the refractive index of the two second dielectric layers 20.

[0035] Light sources such as LEDs can be considered as Lambertian light sources, with constant brightness in all directions. However, the light intensity varies with the angle between the viewing direction and the surface source normal, following a cosine law, exhibiting a characteristic of decreasing intensity as the angle increases. In related technologies without the optical film 1 provided in the embodiments of this application, the light source directly illuminates the panel. For light directly illuminating the area on the panel and directly opposite the light source from the light source, the incident angle is small and the light intensity is high; for light directly illuminating other areas on the panel besides the directly opposite area, the incident angle is large and the light intensity is low. Thus, the light intensity illuminating the panel from the light source exhibits a characteristic of gradually decreasing from the center of the first area outwards, resulting in poor light intensity uniformity when the panel is displaying light.

[0036] When the optical film 1 provided in this embodiment is disposed between the light source and the panel, the light emitted by the light source first illuminates the optical film 1, and refraction and reflection occur simultaneously at the interface between the optical film 1 and the air. Furthermore, light with a smaller incident angle has higher reflectivity and lower transmittance at the interface, while light with a larger incident angle has lower reflectivity and higher transmittance. Thus, light illuminating the optical film 1 and the area directly opposite the light source (hereinafter referred to as the first area) from the light source has a smaller incident angle and undergoes strong reflection at the interface between the optical film 1 and the air, causing more light to be reflected and unable to transmit through the first area of ​​the optical film 1, reducing the transmitted light intensity of the first area. Conversely, light illuminating other areas of the optical film 1 from the light source has a larger incident angle and undergoes weaker reflection at the interface between the optical film 1 and the air, allowing more light to transmit through the other areas of the optical film 1, resulting in higher transmitted light intensity in these other areas. In this way, the transmitted light intensity in the first region on the optical film 1 is reduced, while the transmitted light intensity in other regions is maintained or increased, so that the transmitted light intensity in the first region and other regions tends to be close and relatively balanced, thereby uniformly illuminating the corresponding areas on the panel, so that the light intensity in different areas of the panel is relatively close during light display, achieving a uniform display effect.

[0037] Similarly, when transmitted light enters the optical film 1 and propagates between the first dielectric layer 10 and the second dielectric layer 20, it is simultaneously refracted and reflected at the interface between the first dielectric layer 10 and the second dielectric layer 20. Furthermore, light with a smaller incident angle has higher reflectivity and lower transmittance at the interface, while light with a larger incident angle has lower reflectivity and higher transmittance. For ease of understanding, the following explanation uses the example of light illuminating the first dielectric layer 10 from the second dielectric layer 20; the situation is similar for light illuminating the second dielectric layer 20 from the first dielectric layer 10, but the higher the refractive index of the dielectric layer, the higher the reflectivity at the interface. For light transmitted from the first region of the optical film 1, when light illuminating the first dielectric layer 10 from the second dielectric layer 20, its incident angle is small, resulting in strong reflection at the interface between the first dielectric layer 10 and the second dielectric layer 20. This causes a significant amount of light to be reflected and unable to be transmitted through the portion of the first dielectric layer 10 located in the first region, reducing the intensity of transmitted light in the first region. For light transmitted from areas other than the first region of the optical film 1, when the light shines from the second dielectric layer 20 onto the first dielectric layer 10, its incident angle is relatively small, resulting in weak reflection at the interface between the first dielectric layer 10 and the second dielectric layer 20. This allows more light to be transmitted from the portion of the first dielectric layer 10 other than the first region, resulting in higher transmitted light intensity in areas other than the first region. Thus, the transmitted light intensity in the first region of the optical film 1 is further reduced, while the transmitted light intensity in other regions is maintained or increased. This makes the transmitted light intensity in the first region and other regions tend to be similar and more balanced, thereby uniformly illuminating the corresponding areas on the panel. This ensures that the light intensity in different areas of the panel is relatively similar during light display, achieving a uniform display effect.

[0038] Meanwhile, regarding the reflected light at the interface between the first dielectric layer 10 and the second dielectric layer 20, the reflected light will repeatedly reflect and transmit between the second dielectric layer 20 and the adjacent first dielectric layer 10, gradually diffusing to various areas of the second dielectric layer 20 and transmitting through it. This allows the light originally concentrated in the first area of ​​the optical film 1 to diffuse to other areas. On the one hand, this reduces the intensity of transmitted light in the first area and increases the intensity of transmitted light in other areas, making the intensity of transmitted light in the first area and other areas closer together. On the other hand, it allows the light emitted by light sources at different locations to diffuse laterally, enabling the three primary colors to mix evenly and fully, resulting in a larger number of realistic display colors and meeting color gamut requirements. In this way, light with similar intensity can evenly illuminate the corresponding areas on the panel, making the light intensity in different areas of the panel relatively similar during light display, and producing rich and realistic colors, achieving a uniform display effect.

[0039] Compared to related technologies, the optical film 1 provided in this application embodiment can selectively transmit light emitted from the light source in the vertical direction and diffuse it in the horizontal direction, achieving uniform light intensity in different areas and full mixing of the three primary colors. This results in similar light intensity and rich, realistic colors in different areas of the panel during light display, achieving a uniform display effect. In this application embodiment, no light mixing gap is required between the optical film 1 and the light source, and there is no need to increase the density of the light source arrangement or the thickness or number of light diffusion plates. The application of light diffusion plates can be eliminated, reducing the thickness of the corresponding structure. Furthermore, the optical film 1 itself is thin, allowing for a reduction in the thickness of the direct-lit display device, achieving a lightweight structure. In addition, the optical film 1 provided in this application embodiment does not require alignment with the light source, reducing assembly difficulty and cost, and eliminating the impact of misalignment caused by thermal expansion and contraction on the display effect.

[0040] Because the refractive index of the first dielectric layer 10 is greater than that of the second dielectric layer 20, when light shines from the air or the second dielectric layer 20 onto the first dielectric layer 10, the refracted light (hereinafter referred to as the first refracted light), i.e., the transmitted light, does not undergo a phase abrupt change, while the reflected light (hereinafter referred to as the first reflected light) will have a phase abrupt change of π, resulting in a half-wave loss. The first refracted light propagates within the first dielectric layer 10. When the first refracted light shines from the first dielectric layer 10 onto the air or the second dielectric layer 20 located on the other side, neither the refracted light nor the reflected light (hereinafter referred to as the second reflected light) undergoes a phase abrupt change. Thus, there is a phase difference of π and a path difference of λ1 / 2 between the two reflected beams, which is the wavelength of visible light in the first dielectric layer 10.

[0041] Here, the two reflected beams can be superimposed and amplified by controlling the thickness of the first dielectric layer 10, thereby enhancing the reflected light. In some embodiments, the optical thickness of the first dielectric layer 10 is l1, which is the product of the geometric thickness of the first dielectric layer 10 and its refractive index. Here, l1 can be determined by the following equation:

[0042] Where k is a natural number.

[0043] The optical path length of the first refracted light and the second reflected light it forms within the first dielectric layer 10 is equal to twice the optical thickness of the first dielectric layer 10, i.e., 2l1. Correspondingly, the optical path difference between the second reflected light and the first reflected light is the sum of λ1 / 2 and 2l1, and their phase difference is 2(k+1)π, causing the first and second reflected light to interfere constructively and thus enhance each other. For example, the thickness of the stacked structure is no greater than 0.1 mm.

[0044] As mentioned above, the number of first dielectric layers 10 can be determined according to actual needs, and can be one or more layers; this embodiment does not limit this. In some embodiments, the optical film 1 may include multiple first dielectric layers 10, and the refractive indices of the first dielectric layers 10 located in different layers may be the same or different. Multiple first dielectric layers 10 can further increase the reflection and diffusion effect of light propagating within the optical film 1, and increase the interface reflectivity of the optical film 1 for light with a small incident angle and the transmittance for light with a large incident angle. In some embodiments, the optical film 1 may include multiple first dielectric layers 10, and the thicknesses of the first dielectric layers 10 located in different layers may be the same or different.

[0045] As mentioned above, the number of second dielectric layers 20 can be determined according to actual needs, and can be one or more layers; this application embodiment does not limit this. In some embodiments, the optical film 1 may include multiple layers of second dielectric layers 20, and the refractive indices of the second dielectric layers 20 located in different layers may be the same or different. Multiple layers of second dielectric layers 20 can further increase the reflection and diffusion effect when light propagates within the optical film 1, and increase the interface reflectivity of the optical film 1 for light with a small incident angle and the transmittance for light with a large incident angle. In some embodiments, the optical film 1 may include multiple layers of second dielectric layers 20, and the thicknesses of the second dielectric layers 20 located in different layers may be the same or different.

[0046] In some embodiments, any second dielectric layer 20 is disposed between two first dielectric layers 10. In this way, the outermost dielectric layers on both sides of the stacked structure are first dielectric layers 10, so that when light shines from the air onto the optical film 1, it can come into contact with the first dielectric layer 10 with a higher refractive index, thereby increasing the interface reflectivity.

[0047] like Figure 5 As shown, in some embodiments, the optical film 1 may further include a light-concentrating layer 30, which is disposed on the light-incident side of the stacked structure. The light-concentrating layer 30 can converge the incident light, causing the incident angle of uniformly incident light to converge to a desired angle range, concentrating the incident light into a smaller incident angle range (e.g., less than 45°) and a larger incident angle range (e.g., greater than 67.5°). In this way, the light emitted by the light source first illuminates the light-concentrating layer 30, and after being converged by the light-concentrating layer 30, it illuminates the stacked structure. The concentration of incident light into a smaller incident angle range and a larger incident angle range can increase the interface reflectivity of small-angle incident light on the stacked structure and the transmittance of large-angle incident light on the stacked structure, further shifting the minimum reflectivity point outward, and increasing the diffusion range and diffusion effect of the optical film 1.

[0048] The structure of the light-concentrating layer 30 can be determined according to actual needs, and this application embodiment does not limit it. In some examples, the light-concentrating layer 30 has a prism structure, a pyramid structure, or a convex lens structure. Here, the prism structure, pyramid structure, or convex lens structure can be formed on the surface of the light-concentrating layer 30 facing the stacked structure. The number of light-concentrating layers 30 can be determined according to actual needs, and can be one or more layers, and this application embodiment does not limit it. In some examples, the light-concentrating layer 30 can be multiple layers, and the multiple light-concentrating layers 30 are stacked sequentially. The multiple light-concentrating layers 30 can converge the incident light layer by layer, so that the convergence effect is superimposed and enhanced. For example, the thickness of the light-concentrating layer 30 is no more than 0.2 mm.

[0049] In some embodiments, the optical film 1 may further include a light diffusion layer 40, which is disposed on the light-emitting side of the stacked structure. The light diffusion layer 40 can diffuse the emitted light, effectively expanding the display spot and achieving a uniform display effect.

[0050] The structure of the light diffusion layer 40 can be determined according to actual needs, and this application embodiment does not limit it. In some examples, the light diffusion layer 40 may have a prism structure, a pyramid structure, or a convex lens structure. Here, the prism structure, pyramid structure, or convex lens structure can be formed on the surface of the light diffusion layer 40 facing the stacked structure. The number of light diffusion layers 40 can be determined according to actual needs, and may be one or more layers, and this application embodiment does not limit it. In some examples, the light diffusion layer 40 may be multiple layers, and the multiple light diffusion layers 40 are stacked sequentially. The multiple light diffusion layers 40 can diffuse the emitted light layer by layer, so that the diffusion and expansion effect is superimposed and enhanced. For example, the thickness of the light diffusion layer 40 is no greater than 0.2 mm.

[0051] like Figure 6 As shown, this application embodiment also provides a display module 100, which includes an optical film 1 and a light-emitting unit 2 provided in any of the above embodiments. The optical film 1 has a light-incident side and a light-emitting side disposed opposite to each other, and the light-emitting unit 2 is disposed on the light-incident side of the optical film 1. Here, the light-emitting unit 2 may include a light-emitting light source, and the type of light-emitting light source can be determined according to actual needs, such as Mini LED, Micro LED, etc., and this application embodiment does not limit this.

[0052] In some embodiments, the display module 100 may further include a reflective sheet 3, which is disposed on the side of the light-emitting unit 2 away from the optical film 1. Thus, reflected light from the optical film 1 can illuminate the reflective sheet 3, undergoing multiple reflections and refractions between the optical film 1 and the reflective sheet 3. This causes the reflected light to gradually diffuse to various areas of the surface of the optical film 1, thereby reducing the transmitted light intensity in the first area and increasing the transmitted light intensity in other areas, further bringing the transmitted light intensities of the first area and other areas closer together. Subsequently, the light with similar intensities can uniformly illuminate the corresponding areas on the panel, making the light intensities of different areas of the panel relatively similar during light display, achieving a uniform display effect.

[0053] To further illustrate the practical application effect, a comparative simulation experiment was conducted on the display module 100 and the control group of this application embodiment. Figure 7 In the control group shown, the optical film 1 provided in this embodiment of the application was not disposed between the light source and the panel; wherein, Figure 7 -(a) is the display spot diagram on the panel; Figure 7 -(b) is along Figure 7 - (a) Illuminance distribution diagram obtained by Y-axis sectioning, where the vertical axis is the distance from the center of the light spot and the horizontal axis is the illuminance at the corresponding position; Figure 7 -(c) means along Figure 7 -(a) Illuminance distribution diagram obtained by X-axis sectioning, the vertical axis is the distance from the center of the light spot, and the horizontal axis is the illuminance at the corresponding position; Figure 7 -(d) is the grayscale-illuminance correspondence diagram. Obviously, the display spot on the panel is very concentrated, and the illuminance is concentrated in the central area of ​​the display spot, resulting in low display uniformity.

[0054] Figure 8 This is a simulation diagram of the display module 100 provided in this application embodiment, wherein the optical film 1 provided in this application embodiment is disposed between the light source and the panel. Figure 8 -(a) is the display spot diagram on the panel; Figure 8 -(b) is along Figure 8 - (a) Illuminance distribution diagram obtained by Y-axis sectioning, where the vertical axis is the distance from the center of the light spot and the horizontal axis is the illuminance at the corresponding position; Figure 8 -(c) means along Figure 8 -(a) Illuminance distribution diagram obtained by X-axis sectioning, the vertical axis is the distance from the center of the light spot, and the horizontal axis is the illuminance at the corresponding position; Figure 8 -(d) is the grayscale-illuminance correspondence map. For example... Figure 8 As shown, the display light spots on the panel are distributed relatively evenly, the illuminance in different areas is relatively similar, and the display uniformity is high.

[0055] The optical film and display module provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optical film, characterized in that, For direct-lit displays, including: First dielectric layer; The second dielectric layer and the first dielectric layer are alternately stacked to form a stacked structure, wherein the refractive index of the second dielectric layer is less than the refractive index of the first dielectric layer adjacent to it. When light emitted from the light source shines on the optical film, the reflectivity of light with an incident angle of less than 45° at the interface between the optical film and air is greater than that of light with an incident angle of greater than 67.5° at the interface between the optical film and air, and the transmittance of light with an incident angle of less than 45° at the interface between the optical film and air is less than that of light with an incident angle of greater than 67.5° at the interface between the optical film and air. When transmitted light entering the optical film propagates between the first dielectric layer and the second dielectric layer, the reflectivity of light with an incident angle less than 45° at the interface between the first dielectric layer and the second dielectric layer is greater than that of light with an incident angle greater than 67.5° at the interface between the first dielectric layer and the second dielectric layer, and the transmittance of light with an incident angle less than 45° at the interface between the first dielectric layer and the second dielectric layer is less than that of light with an incident angle greater than 67.5° at the interface between the first dielectric layer and the second dielectric layer.

2. The optical film according to claim 1, characterized in that, Optical thickness of the first dielectric layer l 1 is determined by the following equation: ； in, The wavelength of visible light in the first dielectric layer. k It is a natural number.

3. The optical film according to claim 1, characterized in that, It includes multiple layers of the first dielectric layer, wherein the refractive indices of the first dielectric layers located in different layers are the same or different; and / or, the thicknesses of the first dielectric layers located in different layers are the same or different.

4. The optical film according to claim 1, characterized in that, It includes multiple layers of the second dielectric layer, wherein the refractive indices of the second dielectric layers located in different layers are the same or different; and / or, the thicknesses of the second dielectric layers located in different layers are the same or different.

5. The optical film according to claim 1, characterized in that, Any second dielectric layer is disposed between two first dielectric layers.

6. The optical film according to claim 1, characterized in that, It also includes a light-concentrating layer, which is disposed on the light-incident side of the stacked structure.

7. The optical film according to claim 6, characterized in that, The light-concentrating layer has a prism structure, a pyramid structure, or a convex lens structure; and / or, the light-concentrating layer is multi-layered, with the multiple light-concentrating layers stacked sequentially.

8. The optical film according to claim 1, characterized in that, It also includes a light diffusion layer, which is disposed on the light-emitting side of the stacked structure.

9. The optical film according to claim 8, characterized in that, The light diffusion layer has a prism structure, a pyramid structure, or a convex lens structure; and / or, the light diffusion layer is multi-layered, with the multiple light diffusion layers stacked sequentially.

10. A display module, characterized in that, include: The optical film according to any one of claims 1-9; The light-emitting unit is disposed on the light-incident side of the optical film.

11. The display module according to claim 10, characterized in that, It also includes a reflective sheet, which is disposed on the side of the light-emitting unit away from the optical film.

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